Transducer mounting



June 8, 1965 D. w. FLYGSTAD TRANSDUCER MOUNTING Filed June 17, 1963INVENTOR; .Demv M 7'24-3740 BY United States Patent 3,187,833TRANSBUGJER MQUNTlN- Dean W. Flygstad, Roseville, Minn assignor to TheTelex Corporation, Tulsa, Okla, a corporation of Delaware Filed lune 17,1963, Ser. No. 283,331 Claims. (Cl. 18131) This invention relatesgenerally to transducer mountings and is more particularly directed totransducer mountings for isolating and protecting transducers utilizedin environments subject to undesirable mechanical vibrations anddestructive shock forces.

Although my invention may be useful in many environments, one example ofthe prior art in which transducers must be effectively isolated from theundesirable disturbing effects of mechanical feedback and thedestructive effects of large forces is the hearing aid industry. Due tothe relatively small physical size of transducers utilized in presentday hearing aids, the problem associated with inoperative transducersdue to dropping, for example, the eyeglass type of hearing aid, and theuncomfortable sensations accompanying mechanical feedback through thenecessarily hard and rigid casing for the hearing aid has created a needfor improved transducer mountings. In the usual installation of atransducer in a hearing aid, a physically separate cavity is provided ina housing for the hearing aid assembly and electrical connection is madethrough suitable conductors extending through the housing to theremainder of the electronic portion of the assembly. In many prior artdevices the use of resilient pads and the like and/or resilient tubinghas been utilized to overcome the transducer mounting diificulties. Someof these mounting arrangements have required the use of unnecessarilylarge cavities to accommodate the presence of, for example, foam rubberpads, and the use of pads and the like has failed to produce uniformresults between successive assemblies and in uniform long livedelimination of feedback and the like and in some cases the mounting fortransducers has proven to be complicated and expensive to manufacture.

In one embodiment of my invention I provide a molded two-part sheaththat is adapted to be placed over and in engagement with a transducer,which is normally of. rectangular parallelepiped shaped, and at each ofthe corners of the two-part sheath, or boot, a hollow sphere, openingtoward the inside of the sheath, is provided as an integral part of thesheath so that there is a bubble-like protuberance at each corner of themounting structure. The mounted transducer is then placed in anenclosure, or housing, which is suitably dimensioned to accept thetransducer and sheath so that the spheres at each corner are in contactwith the three mutually perpendicular walls of the housing defining eachcorner thereof.

Thus, I provide an improved transducer mounting which may be easilymanufactured to provide uniform protection from shock and isolation fromfeedback in all three axes of a transducer. It may be easily fabricatedwith a high degree of uniformity from commonly available materials. Thetransducer and mounting may be easily assembled in asmaller housing, orenclosure than heretofore required.

It is therefore an object of my invention to provide an improvedtriaxial transducer mounting which serves to uniformly protect andisolate a transducer.

It is a further object of my invention to provide an improved transducermounting which may be easily fabricated of commonly available materials.

Another object of my invention is to provide an improved transducermounting which may easily be assembled in a smaller housing and that maybe manufactured with a lower degree of tolerance while providingimproved uniformity of operation between assembled units.

Another object of my invention is to provide an im proved transducermounting which comprises a plurality of spherical members on a sheathmounted on a transducer to provide a uniform three axis suspensiontherefor.

A still further object of my invention is to provide improved transducermounting means which comprises a sheath adapted to engage and hold atransducer and which has a plurality of hollow spheres positioned forengagement with a transducer housing.

These and other more detailed and specific objects will be disclosed inthe course of the following specification, reference being had to theaccompanying drawings, in Which FIG. 1 shows a portion of abehind-the-ear type of hearing aid assembly which is broken away to showa transducer and mounting therefor in position in the assembly.

FIG. 2 is a front elevation view of an embodiment of the transducermounting in position on a transducer within a section of a housingtherefor.

FIG. 3 is a side view of the transducer and mounting of P16. 2.

FIG. 4 is a top view of the transducer and mounting of *lG. 2.

FIG. 5 is an enlarged perspective drawing showing one corner of atransducer mounting in position in a housing, or container therefor,from the inside.

FIG. 6 is a plan view, partly in section, of a further embodiment of myinvention.

FIG. 7 is a sectional view of the embodiment shown in FIG. 6 taken alongsection line 7--7.

Referring now to FIG. 1 of the drawing, a housing for a conventionalbehind-the-ear type of hearing aid is indicated generally by thereference character 19. In a behind-the-ear type hearing aid assembly, atube and earpiece (not shown) are connected to the front end and theentire unit is supported on the ear. In the particular embodiment shown,which is representative of a number of commercially available hearingaids, a microphone transducer 15 is mounted within a cavity, or housing12 at the lower rear end of housing 19 which is provided with an opening11 in communication with sources of compressional wave energy.Transducer 15 is shown within a two-part mounting member, indicated byreference characters 13 and 14, each of which is provided with a hollowsphere or protuberance at each corner thereof. It will be understoodthat while I have shown my invention as embodied in a hearing aid, itsapplications and uses are not in any manner restricted to suchembodiment and it is contemplated that those skilled in the art, uponbecoming aware of the principles of my invention, will find uses in manyother environments and applications.

In FIGS. 2, 3, and 4 the several views of the illustrative embodiment ofmy invention show the transducer mounting as a two-part member comprisedof sheaths, or boots, 13 and 14 which are adapted to receive and engagea rectangular transducer 15, which may be of the type commonly used inthe hearing aids. Transducer 15 is provided with an opening 16 for thetransmission of compressional wave energy, and housing It) is providedwith an opening 11 which is adapted to register with opening 16 in soundtransmitting relationship. At each corner of members 13 and 14, there isa hollow sphere Ztl positioned so that its center is coincident with acorner and members 13 and 1d are suitably dimensioned with respect tothe nominal dimensions of the housing, or cavity, 12 so that when thetransducer and mounting are placed Within the cavity each of the sphereson the corners of the mounting is in engagement with the three mutuallyperpendicular sides of housing 12 which define each of the cornerstherein.

In one operative embodiment, members 13 and 14 were fashioned out ofsoft latex material of -15 durometer by a dip process and all of thewall thicknesses, including those of the spheres 211, were .005 inch.The overall length of members 13 and 14 was .420 inch, the height ofeach of members 13 and 14 was .280 inch, and the depth of members 13 and14 was .180 inch. The inside diameter of the spheres 2%) was .031 inch.These dimensions and material when used in combination with a standardcommercially available hearing aid microphone provided a triaxial shockresistance, before the spheres were completely flattened, of gs. Asfurther examples of materials which may be satisfactorily employed forconstructing my invention, a 20 durometer neoprene or silicone rubbermay be employed.

Referring now to the broken away sketch of FIG. 5,

one-corner of member 14-, which includes a spherical protuberation 21),is shown in an attitude which might normally obtain in the absence ofany external forces. At the eight corners in the rectangular cavity ofhousing 12, each of the intersecting mutually perpendicular walls of theillustrated embodiment is in engagement with portions of the spherealong, for example, X, Y and Z axes indicated by the dotted arrows andthere may, or may not, be a slight flattening of the sphere. The areasof contact or engagement are indicated by reference characters 45, 25,and 35 respectively. When a force is directed along any of the axesshown by the dotted arrows, sphere 20 will tend to flatten out or bedeformed so that the respective contact areas 45, 25 and be come largeras the sphere is deformed and the deformation of the sphere will absorbthe energy without damage or transmission of mechanical vibrations tothe transducer contained therein.

It may also be appreciated that deformation of the spheres due to forcesexerted on the transducer may compress the air, or other gas, presentwithin the spheres. Under certain conditions it may prove desirable toutilize this additional energy absorbing medium by constructing thesheath to confine the air within the spheres by providing a snug closefitting engagement with the transducer or, for example, through the useof suitable adhesive materials for attaching the sheath to thetransducer.

Those skilled in the art may appreciate from a consideration of thedrawing of FIG. 5 the triaxial characteristics of my invention and itmay readily be observed that a force applied to the transducer andmounting will be absorbed no matter what direction it may take and thatthe magnitude of the force which may be absorbed is dependent upon themass of the transducer and the physical characteristics of the materialutilized for the mounting.

While I have illustrated my invention as a mounting for a transducerhaving the shape of a rectangular parallelepiped, suitable triaxialmounting characteristics may be obtained with, for example, acylindrical as well as other forms and types of transducers by properplacement of a plurality of spheres of suitable dimension as may bedetermined through experimentation by one skilled in the art uponbecoming familiar with the principles of my invention.

Referring now to FIGS. 6 and 7, a further embodiment of my invention isshown illustrated as applied to a cylindrical form of transducer. InFIGS. 6 and 7, a cylindrical housing dd, which may be fabricated ofsuitable plastic material, is shown adapted to receive a complementaryconfigured cylindrical transducer of substantially the same dimensionsas the inside of a two-part sheath member indicated generally by thereference character 4-1. As may be noted on the drawing, theintersection of the side and end surfaces of the two-part sheath member41 is provided with a plurality of spherical protuberances indicatedgenerally by reference character 42. Sides 43 may be seen to intersectwith ends 44 and 45 of two-part sheath member 41. The protuberances aresuitably dimensioned with respect to the interior dimensions of housing44B and the exterior dimensions of twopart sheath member 4-1 so as toprovide an easily fabricated and efficient mounting arrangement for atransducer to be contained within two-part sheath member 41.

It is understood that suitable modifications may be made in thestructure as disclosed, provided such modifications come within thespirit'and scope of the appended claims. Having now therefore fullyillustrated and described my invention, what I claim to be new anddesire to protect by Letters Patent is:

1. Mounting means for positioning and suspending a transducer ofrectangular parallelepiped shape in a housing therefor comprising, asheath member dimensioned to substantially enclose and hold a transducerof substantially rectangular parallelepiped shape, said sheath memberhaving a hollow protuberance at each corner thereof, said hollowprotuberances being dimensioned to engage corresponding surfaces in ahousing for said transducer.

2. The mounting means of claim 1 in which the hollow protuberances aresubstantially spherical in shape and the center of the spheres iscoincident with the intersection of the three mutually perpendicularsurfaces at each corner of the transducer.

3. The mounting means of claim 2 in which compressible fluid isentrapped in each of the spheres.

4. In combination with a transducer and a complementary configuredhousing therefor, mounting means for resiliently supporting thetransducer in the housing comprising in combination; a sheath memberadapted to substantially enclose a transducer, said transducer and saidsheath member having a plurality of intersecting side portions and saidsheath member having a plurality of spherical protuberances disposed atpredetermined locations and extending outwardly from said intersectionsto resiliently support said transducer in a complementary configuredhousing.

5. The apparatus of claim 4 in which the transducer 7 is a rectangularparallelepiped and the protuberances are disposed at the corners of saidtransducer.

References Cited by the Examiner UNITED STATES PATENTS 2,252,846 8/41Giannini 61. al. 179-180 2,952,748 9/60 P0561! et al. 179-107 3,048,6688/62 WEISS 179-179 FOREIGN PATENTS 556,137 9/43 Great Britain.

LEO SMILOW, Primary Examiner.

1. MOUNTING MEANS FOR POSITIONING AND SUSPENDING A TRANSDUCER OFRECTANGULAR PARALLELEPIPED SHAPE IN A HOUSING THEREFOR COMPRISING, ASHEATH MEMBER DIMENSIONED TO SUBSTANTIALLY ENCLOSE AND HOLD A TRANSDUCEROF SUBSTANTIALLY RECTANGULAR PARALLELEPIPED SHAPE, SAID SHEATH MEMBERHAVING A HOLLOW PROTUBERANCE AT EACH CORNER THEREOF, SAID HOLLOWPROTUBERANCES BEING DIMENSIONED TO ENGAGE CORRESPONDING SURFACES IN AHOUSING FOR SAID TRANSDUCER.